Apparatus for making organic fertilizer



APPARATUS FOR MAKING ORGANIC FERTILIZER Original Filed My 17. 1960 2Sheets-Sheet 1 INVENTOR. ERIC w. swzsolv April :12, 1966 E. w. EWESON IAPPARATUS FOR MAKING ORGANIC FERTILIZER Original Filed May 17. 1960 2Sheets-Sheet 2 INVENTOR. ERIC w Ewzsou AT TOR NE Y5 United States Patent.0

3,245,759 APPARATUS FOR MAKING ORGANIC FERTILIZER Eric W. Eweson, NewYork, N.Y., assignor to International Eweson Corporation, Pine Plains,N.Y., a corporation of New York Original application May 17, 1960, Ser.No. 29,707, now Patent No. 3,138,447, dated June 23, 1964. Divided andthis application Oct. 17, 1963, SeraNo. 316,900

9 Claims. (Cl. 23--259.1)

This application is a divisional application of my application SerialNo. 29,707, filed May 17, 1960, for Method and Apparatus for MakingOrganic Fertilizer, and now Patent No. 3,138,447.

This invention relates to the apparatus for making organic fertilizerfrom organic waste material.

In my prior patents, No. 2,747,836, No. 2,593,867 and No. 2,680,069, Ihave described and claimed a method and apparatus for making organicfertilizer by the decomposition of moist organic material through theaction of aerobic micro organisms in which air is forced through anenclosed mass of such materials from the bottom of the apparatus andspent air and generated gases are withdrawn at vertically spacedintervals throughout the mass.

While the methods and apparatus disclosed in my prior patents aresatisfactory for the production of organic fertilizer, greater speed inlarge scale quantities is desirable.

I have discovered that decomposition rate can be increased and thevolume of compressed air needed for aeration can be decreased ifmicrobial inoculation of the organic material and aeration for theprocess is effected in accordance with the method of the presentinvention.

Microbial inoculation .with a portion of the finished product has beenused in the manufacture of bakers yeast. However, yeast fermentationentails the propagation of only one species of micro organisms (theSaccharomyces cerevisiae fungi) and such propagation is made insolutions.

Inoculation of non-liquid moist organic material with substantialquantities of the finished product as a culture has been attempted,based on the assumption that composting is analogous to manufacture ofbakers yeast. However, while yeast manufacture involves one species ofmicro organism, compost manufacture involves the propagation in moistsolids of a great number of differ ent types and species of microorganisms with greatly varying climatic requirements, and thepredominant microbial floras change drastically and frequently duringthe progress of the process.

For this reason, following the inoculation practice of the yeastindustry has not been successful in the manufacture of compost.

Similarly, inoculation of the raw material by small quantities ofspecial, expensive and often secret microbial cultures, which are soldcommercially to stimulate compost fermentation, does not improve eitherprocessing speed or the quality of the finished product. (See pages6062, Technical Bulletin No. 9, Series 37, June 1953, which reports theresults of research by the Sanitary Research Project, University ofCalifornia, Berkeley, California.) In addition to the small amounts ofinoculants used, the reason for this result is that the inoculant isgrown under different conditions and material than encountered when theyare used. This lack of acclimatization makes them ineffective.

While more complex in reality, compost processing can be practiced inaccordance with this invention by considering composting as afermentation process progressing' in at least three, but preferablyfour, microbiologi- Patented Apr. 12, 1966 cally distinct stages. Thefirst stage of fermentation is dominated by highly thermophilic speciesof micro organisms creating temperatures as high as 170 F. The secondstage of the process is carried on by moderately thermophilic microbesat about 150 F. The following two stages are characterized by mesophilicmicrobial activities with temperatures ranging from about 125 F. in thethird stage down to about F. in the fourth and last stage.

Variations in carbon dioxide concentration of the air in thefermentation masses in such stages are even greater being as high as 14%(-350 times that in the atmosphere) in the first stage, from 58% in thesecond stage, from 2-5 in the third stage, and less than 1% in the finalmesophilic stage of the process.

Similarly, the stages may be characterized by their predominant groupsand species of micro organisms. Thermophilic fungi predominate in thefirst stage if the raw material contains appreciable quantities ofeasily assimilable carbohydrates; otherwise thermophilic bacteria arethe most active. Moderately thermophilic bacteria predominate during thesecond stage. Mesophilic bacteria are the most active micro organisms inthe third stage. The fourth stage is characterized by the activities ofmesophilic bacteria and actinomycetes.

It is, therefore, one object of this invention to provide an improvedmethod for fermentation of moist organic materials in which the materialis treated in stages, the climate in each stage is controlled foroptimum growth of the stage micro organisms, and the material in eachstage inoculated with micro organisms developed in the climate of thestage.

It is a further object of this invention to provide an improvedapparatus for carrying out of compost fermentation.

In accordance with these objects, and in accordance with the preferredpractice of the method of this invention, the raw organic material istreated in stages. The climate in each stage is maintained for theoptimum development of the types and species of the micro organismspredominant in that stage. In each stage, the material is inoculatedwith the predominant types of micro organisms which have :been culturedin the stage climate. After treatment, the material is excessivelyaerated to arrest the fermentation, free the material from generatedgases and dry it for bagging and shipping.

F or practice of this method, I have provided, in its preferred form, adigester mounted for rotation about an axis inclined to the horizontal.The digester is divided into compartments by partitions spaced along theaxis of rotation. Each partition is provided with transfer buckets whichare selectably opened and which, when opened, transfer material fromcompartment to the next lower compartment without allowing significantchange in the climate of the connected compartments.

Air is forced through the entire digester from the lower end thereof,and spent air is selectably vented from each stage of compartment tomaintainthe climate therein optimum for the micro organisms predominantin such stage. A portion of the treated material is left in each stageas a culture for inoculation of transferred material and the entiredigester is rotated to ensure efficient aeration and complete mixingwith and inoculation of the transferred material.

A preferred embodiment of the apparatus according to this inventionwhich is suitable for carrying out the method of this invention is shownin the accompanying drawing, of which:

FIG. 1 is a vertical cross section through the apparatus;

lFIG. 2 is a section taken along lines 2-42 of (FIG. 1;

3 FIG. 3 is a section taken along lines 3-3 of FIG. 1; 'FIG. 4 is anenlarged section throughone of the air distributor valves in theapparatus shown in FIG. 1; and FIG. is a section taken along lines 5-5of FIG. 1. In the figures, there is shown a digester 1 comprising a drummounted on bearing blocks 2 for rotation about an axis 3 which isslightly inclined with respect to the horizon 4 to allow gravity feed ofthe material through the length of the drum.

At each of the bearing points, a suitable bearing 5 is provided forrotatable mounting of the drum. The drum may be rotatably driven bymotor 6 through the cooperation of pinion 7 on the drive shaft 8 thereofwith the annular gear 9 surrounding the drum. A suitable reduction gear11 is often desirable.

The digester is divided into four fermentation chambers 10, 12, 14 and16 by partitions 18, 20, 22 respectively. A screening chamber 24 isseparated from the digester by partition 26 and a drying chamber 28 isseparated from fermentation chamber 16 by partition 30.

The raw material, such as municipal garbage, is introduced into thedigester through hopper 33 on the stationary casing 34 of a screwconveyor 36. The material is discharged on the far end of conical screen38. The screen 38 is fixedly mounted to the digester end wall 40 andpartition 26 and is pitched so that the material will move towards theend wall 40 during screening.

The screen is, of course, mesh, with not less than 2 inch openings,since only coarse screening or grinding of the material is necessary.The tailings, such. as shoes, stones, metal objects and other heavynon-decomposable objects which abound in municipal refuse, aid in thescreening and grinding. The tailings collect near the end wall 40 andmay be periodically removed through port 41. Alternatively, the tailingsmay be picked up by flanges or baflles 42 which deposit the tailings inhopper 44. The tailings may then be extracted by opening the dischargedoor 46 and reversing the screw conveyor drive. During screening, thetailings may be recirculated through hopper 44 to aid in grinding andscreening material or the hopper may be mechanically closed.

The screened material is transferred from compartment 48 to compartment10 of the digester by means of transt fer buckets or pockets 50. Thetransfer pocket in the partition is merely a box open to the upper stage(here compartment 48) and is provided with a hinged bottom 52. Thepockets fill with material and when gravity opens the bottom, thematerial is discharged into the successive compartment. The transfercan, thus, be made from a partially filled chamber even though thesubsequent chamber is quite full. To preclude material transfer untildesired, the buckets are provided with lock toggles 54 operable fromoutside the digester.

Similarly, partitions 18, 20, 22 and Marc provided with transferpockets. In these partitions, however, the opening 56 to the pocket isdisplaced from the periphery of the partition to prevent completeemptying of chambers 10, 12, 14 and 16 respectively.

To unload the digester, there is provided transfer buckets 58 which feedmaterial from chamber 28 to the discharge air lock 60 via chute 62 inthe non-rotating discharge end 61 of the digester. The air lock isprovided with a plurality of vanes 64 which are rotatably driven todischarge material without opening chamber 28 to the atmosphere.

Control of the climate in each of the fermentation chambers 10, 12, 14and 16 and drying chamber 28 is best understood by assuming thatmaterial under fermentation is enclosed therein.

Air is forced through the entire digester by compressor 66 driven bymotor 68 and introduced into the digester via pipe 70 and valve 72. Theair passes through an air hole or passage 74 in the periphery of eachpartition.

To prevent material from passing through or clogging the passage, .aguard structure 76 is provided. By positioning the air holes instaggered relationship in adjacent partition, movement of the airthrough the fermenting mass is ensured. For example, if passages inadjacent partitions are at diagonally opposed position, the air takes azigzag path through the digester passing through all the materialtherein.

As the air passes through the chambers, it picks up generated gases,particularly CO Thus, the concentration increases through the digesterchambers. To control the aeration flow and, thus, to control the climateof each compartment to provide optimum conditions for growth of thepredominant micro organisms in each chamber, there is provided a valve78 to bleed off excess air and gases from the chamber through passage8-0. The screen compartment is vented by vent 82 which need not bevalved since all residual gases are exhausted therethrough.

The method of the invention may best be seen by assuming that allchambers are loaded with material inoculated with the predominant microorganisms for each stage. The digester is rotated and air forcedin thedrying chamber 28 in proper quantity and, if desired, at an elevatedtemperature to better dry the material to baggable dryness. As the.drying flow normally will exceed the aeration flow necessary in chamber16, a portion of the air must be valved to the atmosphere through thevalve in air passage 74 through partition 30 and only the remainder ofthe air forced into compartment 16. The fermenting mass is, thus,properly aerated to stimulate fermentation without over-aeration orunder-aeration either of which inhibits such fermentation. The airpassing therethrough now gains in temperature, humidity and COconcentrations. Portions of this air are passed into chamber 14 forclimatic control thereof. Similarly, the process is repeated forchambers 12 and 10.

The exact quantities of air for each chamber are most easily determinedby temperatures and CO concentrations of the fermenting mass. However,for guidance, I have found that the maximum requirements for It will beappreciated that the quantities of air necessary for aeration arestrictly prorationed, are very low in comparison with other types ofprocessing and that no fresh atmospheric air reaches the material at anyof the fermenting stages. The tumbling of the material in the drumprevents air channel formation and thereby ensures aeration.

In operation, the digester .will normally be controlled to provide theproper climatic conditions for each of the fermentation chambers inaccordance with the requirements of temperature and CO concentrations asset forth above. The air flow will fall within the suggested ranges andnormally will be further controlled by the operator by measurement ofthe temperature and the CO concentration in each chamber. If, forexample, the CO concentration of the air in the mass falls below thatestablished for proper climatic control in which case the temperature isalso likely to be too low, this will serve as an indication that thechamber is receiving excessive aeration air flow and the valve in theair passage through the partition next below the chamber can be openedto release more air to the atmosphere. On the other hand, if thetemperatures exceed the optimum temperatures desired and the COconcentrations are too high, this is an indication that too littleaeration air is being received by the chamber and the valves can bepartially shut.

When the fermentation in chamber 16 is completed, the material can betransferred-to thedrying chamber 28 to arrest the process and dry thematerial to the proper dryness for packaging. However, since thetransfer pockets are displaced from the periphery of the chamber, afixed quantity of the material will remain in the chamber. This materialserves as an inoculant for new material in this chamber. It will benoted that the predominant micro organisms for the stage of fermentationare at the optimum of development and the chamber climate is maintainedat optimum conditions for development of such micro organisms in the newmaterial.

Thus, when the material in chamber 14 is transferred to chamber 16, therotation of the digester Will thoroughly mix the new material with thematerial remaining in chamber 16 to thoroughly inoculate the newmaterial with the developed bacteria. The inoculation by complete mixingis necessary due to the low migration rate of the micro organisms.Similarly, the inoculation is effective since the climate is maintainedwith such conditions as to nurture the development of the specific microorganisms in this stage of fermentation.

Similarly, the materials in chambers and 12 are transferred from stageto stage of fermentation and new material is added to chamber 10 asnecessary.

In this manner, considerable quantities of material can be processed inrelatively short time in a stepped-flow type of process which becomesvirtually a continuous flow process. In one digester, as much as 50 tonsof material may be processed in each fermentation chamber and willcomplete its development Within a 24 to 48 hour period depending on thetype of material processed.

Thus, it can be seen that composting in specific stages of aerobicfermentation in which each stage is inoculated with the predominantmicro organisms for that stage in a climate controlled to provideoptimum development of each group of such predominant micro organismsgreatly increases the efiiciency of the compost manufacturing processand improves the quality of the resultant fertilizer. The completedprocess results in a decomposed and permanently stabilized product whichwill not under-go renewed fermentation and putrefication when thematerial is bagged or put in piles with the air supply cut off.

This invention may be variously modified and embodied within the scopeof the subjoined claims.

What is claimed is:

1. Apparatus for the manufacture of organic fertilizer by the treatmentof moist natural organic material with successive groups of aerobicmicro organisms which comprises a digester, said digester being mountedfor rotation about an axis, said digester being divided by partitionsinto compartments for each successive group of micro organisms, transferbuckets associated with each of said partitions to fransfer materialfrom one compartment to the next lower compartment, said transferbuckets being selectively operated to transfer material betweencompartments only when desired, a compressor to force air through saiddigester from the last compartment thereof, a valve associated with eachcompartment to vent spent air and gases from each of said compartments,to control the CO content and temperature of each compartment at thelevel conducive to optimum reproduction of the group of micro organismscontained therein, and means to rotate said digester.

2. Apparatus in accordance with claim 1 which includes means forscreening said material prior to transfer of said material into saiddigester.

3. Apparatus in accordance with claim 1 in which said transfer bucketsare positioned so that a portion of the material treated in eachfermentation compartment remain in the compartment for inoculation ofsubsequent batches of material.

4. Apparatus in accordance with claim 1 in which transfer buckets arepositioned along the periphery of said partition, each of said transferbuckets comprising a pocket having an opening thereto formed in saidpartition, said bucket being formed with a bottom wall hingedly coupledto said bucket, whereby during rotation of said digester said bucketswill be filled through said opening as a bucket is at the bottomposition of the digester and will empty the contents into the nextcompartment as the bucket is reaching the top position during digesterrotation.

5. Apparatus in accordance with claim 4 which includes means for lockingthe bottom Wall of said transfer bucket in the closed position.

6. Apparatus in accordance with claim 4 which inpassages are providedthrough each of said partitions, the passages through adjacentpartitions being staggered in positions to force air through thematerial in each chamher and prevent direct air passage through thechamber without passing through said material.

7. Apparatus in accordance with claim 6 in which said valves arepositioned within said air passages.

8. Apparatus in accordance with claim 6 which includes guard structuressurrounding each of said passages to prevent material being processedfrom obstructing said passages.

9. A digester for the fermentation of natural organic materialcomprising a drum mounted for rotation about its central axis, aplurality of partitions positioned within said drum to divide the druminto a series of intermediate treatment compartments, a screeningcompartment at one end of said drum and a drying compartment at theother end of said drum, the axis of said drum being inclined from thehorizontal with the screening compartment elevated with respect to thedrying compartment, a screen mounted within said screening compartmentand atfixed to the partition forming said compartment to rotate withrotation of said drum, means for introducing said material into saidscreening compartment, selectively operable transfer buckets in each ofsaid partitions to move material from a higher to a lower compartment,means for forcing air into said digester and to cause said air to movefrom said drying compartment through the drum to said screeningcompartment and valve means in each compartment to exhaust a selectableportion of said air in said compartment to the atmosphere.

No references cited.

MORRIS O. WOLK, Primary Examiner. JAMES H. TAY MAN, IR., AssistantExaminer,

1. APPARATUS FOR THE MANUFACTURE OF ORGANIC FERTILIZER BY THE TREATMENTOF MOIST NATURAL ORGANIC MATERIAL WITH SUCESSIVE GROUPS OF AEROBIC MICROORGANISMS WHICH COMPRISES A DIGESTER, SAID DIGESTER BEING MOUNTED FORROTATION ABOUT AN AXIS, SAID DIGESTER BEING DIVIDED BY PARTITIONS INTOCOMPARTMENTS FOR EACH SUCCESSIVE GROUP OF MICRO ORGANISMS, TRANSFERBUCKETS ASSOCIATED WITH EACH OF SAID PARTITIONS TO TRANSFER MATERIALFROM ONE COMPARTMENT TO TO THE NEXT LOWER COMPARTMENT, SAID TRANSFERBUCKETS BEING SELECTIVELY OPERATED TO TRANSFER MATERIAL BETWEENCOMPARTMENTS ONLY WHEN DESIRED, A COMPRESSOR TO FORCE AIR THROUGH SAIDDIGESTER FROM THE LAST COMPARTMENT THEREOF, A VALVE ASSOCIATED WITH EACHCOMPARTMENT TO VENT SPENT AIR AND GASES FROM EACH OF SAID COMPARTMENTS,TO CONTROL THE CO2 CONTENT AND TEMPERATURE OF EACH COMPARTMENT AT THELEVEL CONDUCIVE TO OPTIMUM REPRODUCTION OF THE GROUP OF MICRO ORGANISMSCONTAINED THEREIN, AND MEANS TO ROTATE SAID DIGESTER.